Memory devices can be provided as internal, semiconductor, integrated circuits in computers or other electronic devices and systems. There are many different types of memory including random-access memory (RAM), read only memory (ROM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), and flash memory, among others.
Flash memory devices are utilized as non-volatile memory for a wide range of electronic applications. Flash memory devices often use a one-transistor memory cell that allows for high memory densities, high reliability, and low power consumption. Uses for flash memory include memory for personal computers, personal digital assistants (PDAs), digital cameras, and cellular telephones, among others.
Power-on reset (POR) circuitry is often used in memory devices to insure proper functionality of the device when power is initially applied to the device, e.g., during power on of the device, and to insure proper functionality of the device if power to the device is temporarily lost. Power-on reset circuits can prevent various internal logic circuits of the device from functioning until after the power-on reset circuit determines that the applied supply voltage, e.g., Vcc, is adequate. In various instances, the applied supply voltage that is adequate to insure proper functioning of the internal circuit can vary depending on the type of logic circuit and/or the particular function of the circuit.
For example, internal logic circuits may include logical data latches whose output signal may be reset when the supply voltage reaches a first level, but whose output signal may not present an accurate value until the supply voltage reaches a different level, e.g., a higher level at which the output signal of the latches is accurate. Other examples of internal logic circuits of a device which a POR circuit may prevent from functioning until the POR circuit determines that the applied supply voltage is adequate can include, but are not limited to, reference voltage circuits and charge pump circuits.